Hi Pippa,
Probably not much of an answer, but this link provides some useful help and support.
http://www.spig.clara.net/
I think that in general terms, courts can be sympathetic to the emotional tensions of such cases. Joint orders are not particularly common as the courts view a child needs the stability of a single home, but at the age of 14 and at the request of your stepdaughter, it is quite likely that it may well be granted if it is seen as a benefit to her � even if her mother is hostile to the idea. A child her age will be given her own representation.
Mr P, and the S/D need to demonstrate that an order would be in the interest of the child in accordance with the requirements of s1 Children Act 1989 which makes the interests of the child the first and paramount concern. It is unlikely that a �rebuttable presumption� can be disputed as the S/D is old enough to cope with home sharing. If the mother is particularly hostile, then the Local Authority will make an investigation under s37 Children Act 1989 and make their report to the court.
With a joint order comes joint responsibility � which I presume Mr P is well aware and doing anyway � which can be financial etc.
Good luck.